Valve mechanism for rock drills



G. H. FUEHRER VALVE MECHANISM FOR ROCK DRILLS Sept. 2, 1941.

Filed April 4, 1940 INVENTOR HIS ATTORNEY Patented Sept. 2, 1941 UNITED T FFICE Ingersoll-Rand Company, New York, corporation of New Jersey N. Y., a

Application April l, 1940, Serial. No. 327,772

(Cl. 121l9) 7' Claims.

This invention relates to rock drills, and more particularly to a valve, mechanism for rock drills of, the fluid actuated type.

One object of the invention is to obtain a rapid and eflicient distribution of pressure fluid to the ends of the piston chamber for actuating the piston.

Another object is to assure a powerful blow of the piston with aminimum charge of pressure fluid.

Other objects will be in part obvious and in part pointed out hereinafter.

In the drawing accompanying this specification and in which similar reference numerals refer to similar parts,

Figures 1 and 2 are elevations, partly broken away, of a rock drill equipped with valve mechanism constructed in accordance with the practice of the invention and showing the valves in the extreme positions which they will occupy in practice.

Referring more particularly to the drawing, 23 designates, in general, a rock drill comprising a cylinder 2| having a piston chamber 22 to accornmodate a reciprocatory hammer piston 23. Intermediate the ends of the piston chamber 22 are a pair of exhaust ports 24 that are controlled by the piston 23 and a closure 25 for the front end of the piston chamber serves as a guide for a working implement of which the shank 26 is shown extending into the front end of the piston chamber 22 to receive the blows of the hammer piston 23.

The rearward end of the cylinder 21 is closed by a back head 21 having an annular flange 2-8 extending into the cylinder. The flange 28 defines a chamber 29 into which pressure fluid is conveyed by a passage 30 in the back head 2'! and opening into a valve chamber 3| containing a throttle valve 32. ably of the rotary type and has a bore 33 that may be in constant communication with the source of pressure fluid supply, and in the wall of the throttle valve is a port 34 to afford communication between the bore 33 and the passage 39.

The bore 35 in the cylinder 2| into which the flange 28 extends is enlarged somewhat to accommodate valve mechanism, designated in its entirety by 36. The valve mechanism comprises a valve chest 37 which seats upon a shoulder 38 be pressed against the valve chest, to hold it im- The throttle valve is prefermovable in, the bore 35, by the usual side rods (not shown) but which may extend along the sides of the rock drill to clampthe casing parts together.

The, valve chest 37, in the form of the invention illustrated,.. comprises two members 39 and 43. The latter is seated on the shoulder 38 and is in the form of a sleevez'of which the rear end serves as a seat for the member 39, and on the member 39 is a plug portion 4| that extends into the member 40 and cooperates therewith to define a valve chamber 42 of which a rearwardly extending annular portion 43 lies between the periphery of the plug and the encircling sleeve.

A. port 45 in a wall 54 at the front end of the valve chamber aifords communication between the valve chamber 4.2 and the rearward end of the. piston chamber 22, and at the side of the front end of the valve chamber 42 is an inlet passage 43 which leads to the front end of the piston chamber 22 and has a restricted port 4'! at its front end opening into the piston chamber. A second port 48 of larger flow areathan the port 4'! opens into the piston chamber rearwardly of the port '41.

In order to maintain the pressure fluid consumption. toaminimum and to assure a powerful and effectivebl'ow of the hammer piston, each inlet passage is controlled by a separate valve. The admission of pressure fluid into the rear inlet passage 45 is accordingly controlled by a valve 49 comprising a flange 5!! that seats upon a seating surface 5i encircling the port 55 to cutoff communication between the valve chamber 52,

'- the rear endof the piston chamber by the piston to assist in throwing the valve 49- rearwardly;

On the rearward side of the flange St is a stem 55 which extends slidably into a bore 55 in the plug 4! and the rear end of the bore 56 is vented to the atmosphere by a passage 51 extending through the member 49 and the cylinder 2|.

The stem 55 is preferably hollow to lighten the valve and the outer portion of the rearward side of the flange serves as a-pressure surface 58 that is constantly subjected to the pressurefluid in the valve chamber. The annular zone 59 between the pressure surface 58 and the stem 55 cooperates with a seating surface 59 on the front end of the plug 4| to limit the rearward movement of the valve and said zone 59, together with the pressure surface 58, serves as a holding surface which is subjected to pressure fluid to hold the valve forwardly against the seating surface 5|.

The valve 6| that controls the admission of pressure fluid into the inlet passage 46 is in the form of a sleeve slidable in the annular portion 43 of the valve chamber and has a flange 62 at its front end that encircles the flang and is spaced therefrom to define an annular passage 63 through which all the pressure fluid used for actuating the piston passes to the ends of the piston chamber. On the front end of the flange 62 is an annular actuating surface 64 which is constantly exposed to pressure fluid tending to throw the valve 6| rearwardly. A shoulder lying rearwardly of the actuating surface 64 presents an annular surface that seats upon a surface 66, on the wall 44, encircling the seating surface 5| to limit the forward movement of the valve GI, and on the rearward surface of the introverted portion of the flange 62 is a surface 6! which cooperates with an annular seating surface 68 on the plug 4! to limit the rearward movement of the valve 6 I.

The valve 6| is, moreover, provided with an external flange 69 at its opposite end having a rear actuating surface 10 which is intermittently subjected to air compressed by the piston from the rear end of the piston chamber 22, and such compression is conveyed to the actuating surface 10 by a passage H connecting the rear ends of the piston chamber 22 and the valve chamber 42.

As a preferred form of construction, means are provided to avoid the formation of compression in the front end of the piston chamber and a consequent cushioning of the blow of the hammer piston. To this end the sleeve portion of the valve 6| is provided with a peripheral groove 12 to afford communication between the front inlet passage 46 and an atmospheric vent 13 in the valve chest and the cylinder and opening into the annular portion 43 of the valve chamber. A vent 14 is also formed in the valve chest and the cylin-der to communicate th forward surface of the flange 69 with the atmosphere.

The operation of the device is as follows: With the valves 49 and 6|, respectively, in the rearmost and foremost limiting positions, as illustrated in Figure 1, pressure fluid passing through the annular passage 63 enters the rear end of the piston chamber and drives the piston 23 forwardly against the working implement. The valves will be held in the positions described by pressure fluid acting against the entire front surface of the valve 49 and against the surfaces 61 and 19 of the valve 6|. At the instant the piston 23 uncovers the rearmost exhaust port 24 the pressure beneath the valve 49will drop and the pressure fluid acting against the pressure surface 58 will then drive the valve 49 forwardly against the seating surface 5! where it will be held immovable by pressur fluid acting against the entire rear surface of the flange 59,

Upon the exhaust of pressure fluid in the rearward end of the piston chamber 22 the pressure acting against the surface 10 of the valve 6! will also drop and the pressure acting against the constant pressure area 64 will then move the valve 6| rearwardly to admit pressure fluid to the front end of the piston chamber for returning the piston 23. This movement of the valve 6| will take place simultaneously with the forward movement of the valve 49 and immediately prior to or at the instant of the delivery of the blow of the hammer piston against the working implement. With the valves in the positions described the annular groove 12 will effect communication between the front inlet passage 46 and the vent l3 and the air entrapped in the front end of the piston chamber may then escape through these channels to the atmosphere.

In the new position of the valve 6| communication will be established between the annular passage 63 and the front inlet passage 46. Pressure fluid will then flow into the front end of the piston chamber and return the piston to its initial position. During this movement of the piston and after the piston has covered the rearmost exhaust port 24 the air in the rear end of the piston chamber will be compressed and will act against the pressure area 54 of the valve 49 and the actuating surface 10. The compression acting against the surface 54 will be augmented by the live pressure fluid acting against the pressure area 52. These forces will then throw the valve 49 rearwardly to its initial position and the compression acting against the surface 10 will throw the valve forwardly against the seating surface 66 and out off the further flow of pressure fluid to the front end of the piston chamber, thus completing the cycle of operations.

I claim:

1. In a fluid actuated rock drill, the combination of a casing having a piston chamber and a reciprocatory piston therein, a valve chamber in the casing, inlet passages leading from the same end of the valve chamber to the ends of the piston chamber, a valve in the valve chamher to control the flow of pressure fluid into one inlet passage, and another valve in the valve chamber to control the flow of pressure fluid into another inlet passage.

2. In a fluid actuated rock'drill, the combination of a casing having a piston chamber and a reciprocatory piston therein, a valve chamber in the casing, inlet passages leading from the valve chamber to the ends of the piston chamber, a valve in the valve chamber to control the flow of pressure fluid into one inlet passage, and a second valve in the valve chamber encircling the first mentioned valve to control the flow of pressure fluid to another inlet passage.

3. In a fluid actuated rock drill, the combination of a casing having a piston chamber and a reciprocatory piston therein, a valve chest having a valve chamber, inlet passages leading from the same end of the valve chamber to the ends of the piston chamber, a pair of valves in the valve chamber, each valve having a portion to control the flow of pressure fluid to an inlet passage, and a passage defined by the portions for conveying all the pressure fluid flowing to the inlet passages.

4. In a fluid actuated rook drill, the combinatlon of a casing having a piston chamber and a reciprocatory piston therein, a valve chest having a valve chamber, inlet passages leading from the valve chamber to the piston chamber, a pair of valves in the valve chamber arranged con centrically with respect to each other and each valve having a flange to control an inlet passage, an annular passage defined by the flanges for conveying all the pressure fluid flowing to the inlet passages, concentrically arranged bearing recesses in the valve chest, and extensions on the valve slidable in the recesses to guide the valves.

5. In a fluid actuated rock drill, the combination of a casing having a piston chamber and a reciprocatory piston therein, a valve chest having a valve chamber, inlet passages leading from the valve chamber to the piston chamber, a valve in the valve chamber to control one inlet passage having an actuating surface constantly exposed to pressure fluid for throwing the valve in one direction, an opposed actuating surface on the valve having a portion subjected constantly to pressure fluid and another portion subjected intermittently to compression from the piston chamber to throw the valve in an opposite direction, a second valve arranged concentrically with the first said valve to control the flow of pressure fluid to another inlet passage and having an actuating surface constantly exposed to pressure fluid for throwing said second valve in one direction and having an opposed actuating surface intermittently subjected to compression from the piston chamber to throw said second valve in an opposite direction.

6. In a fluid actuated rock drill, the combination of a casing having a piston chamber and a reciprocatory piston therein, a valve chest having a valve chamber, rear and front inlet passages for the piston chamber opening into the valve chamber, a valve in the valve chamber having a flange to control the rear inlet passage and a stem to guide the valve, opposed actuating surfaces on the valve subjected to fluid under pressure for throwing the valve, a second valve in the valve chamber to control the flow of pressure fluid to the front inlet passage and having a flange to encircle the first mentioned flange, opposed actuating surfaces on said second valve subjected to fluid under pressure for throwing said second valve, and an annular passage between the flanges for conveying pressure fluid to the inlet passages.

7. In a fluid actuated rock drill, the combination of a casing having a piston chamber and a reciprocatory piston therein, a valve chest having a valve chamber, rear and front inlet passages for the piston chamber opening into the valve chamber, a valve in the valve chamber having a flange to control the rear inlet passage and a stem to guide the valve, opposed actuating surfaces on the valve subjected to fluid under pressure for throwing the valve, a second valve in the valve chamber to control the flow of pressure fluid to the front inlet passage and having a flange to encircle the first mentioned flange, opposed actuating surfaces on said second valve subjected to fluid under pressure for throwing said second valve, an annular passage between the flanges for conveying pressure fluid to the inlet passages, an atmospheric vent in the valve chest, and an annular groove in the said second valve to afford communication between the front inlet passage and the atmospheric vent to provide an escape for compression from the front end of the piston chamber.

GEORGE H. FUEHRER. 

